I wodn a brand new 8102.
I have had a lot situations where the ARC is not working after starting the TV from sleep state.
Usually jumping between HDMI sources returns the ARC to function but sometimes one has to re-choose “HDMI audio output” from the sound options although it is on already. Sometimes TV has to be rebooted totally. Sometimes nothing works. This FW was the first FW I used the TV with so I have no idea how it worked earlier.
All this might be ofc because of my AVR or HDMI-cable or both.
On a side note, for some reason when the ARC is working, I can see it by looking at the AVR cos it shows Dolby DD icon on it, even though I am only in the Android Homescreen. It shows the DD icon even though I watch stereo stuff, and ofc the sound comes out as a stereo. Weird. It does not matter if I
DTS is not working thru Kodi. It plays as DD or DD+. Afaik Philips FW is not standard API24 which is the reason for this. If I connect Mi Box to TV, then I get DTS to the AVR even though all this goes thru TV and ARC. Although there is a 0.2s delay in the sound so I have to off set the audio thru Kodi.
The internal player pretty much crashes every time I try to watch any 4K material with it. Useless junk.
Sorry for the english post aber meine deutsch ist nicht das gut.